Safety and potency studies of HIV DNA vaccines

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Since both humoral and cellular and immune responses may be important against AIDS, two HIV-1 multigenic plasmid DNAs were constructed containing the gag and env genes from pNL4-3 DNA under the regulation of the human CMV and murine endogenous AKV promoters. Development of humoral and T cell proliferative immune responses were analyzed by direct DNA injection of rhesus and pig-tailed macaques. Similar levels of T-cell proliferative responses were generated with both DNAs in rhesus macaques whereas the humoral responses in rhesus and pig-tailed macaques correlated directly with the promoter strength of the vaccine DNA. Long- term, boostable antibodies to Gag and Env were generated using less amount and fewer injections of CMV-DNA than with AKV-DNA. Tetanus toxoid injection was used to demonstrate ability of the animals to respond similarly to a known antigen. To evaluate protection against HIV-1, DNA vaccinated rhesus macaques were boosted with a single injection of oligomeric gp160 (to enhance the env response). Evaluation of the Env antibody responses at 4 weeks post-boost indicated about an increase in the antibody titer to gp120 and gp41 in the HIV-1 DNA vaccinated animal as compared with the control animals. The animals were challenged with SHIV-IIIb. At 4 weeks post-protein boost, the HIV-1 DNA vacine + protein immunization resulted in reduction of plasma viral RNA indicating that the animals were partially protected. Similar analysis are currently underway in HIV-1 DNA vaccinated pig-tailed macaques which have been challenged with HIV-1.